About our Moon and the Lunar Reconnaissance Orbiter Mission

NASA’s LRO Leads the Way to the Moon and Beyond!

NASA's Lunar Reconnaissance Orbiter (LRO) is a robotic that is gathering high-resolution data about the lunar surface and surrounding environment. LRO launched on June 18, 2009, from Kennedy Space Center and is currently orbiting the Moon. Its primary mission is to spend one year in a polar orbit collecting detailed information about the Moon's environment.

Packed inside and on the exterior of LRO are a variety of instruments, computers, fuel tanks, batteries, solar arrays, and an antenna that the spacecraft uses to survey our nearest neighbor. In total, LRO weighs roughly 2200 pounds (about 1000 kilograms) and is about the size of a 15-passenger van. Its solar arrays supply 100 W of power to the onboard lithium-ion batteries, which provide the spacecraft's electricity. LRO uses the stars to guide its journey: The spacecraft's computers use the data from two onboard star-trackers to determine and adjust LRO's orientation in space. LRO has two internal fuel tanks, which burn hydrazine fuel to maneuver the spacecraft. LRO is outfitted with seven scientific instruments that are helping us learn more about the lunar environment. A radio antenna transmits the instruments' images, topography and temperature measurements, and other data back to scientists on Earth.

Artist's conception of LRO orbiting the Moon with Earth pictured in the distance. A variety of instruments on LRO will be used to better understand the lunar environment. The Image courtesy of NASA.

LRO encircles the Moon from a height of only 31 miles (50 kilometers), giving its instruments an up-close view of the surface. Its orbit carries it directly over the poles in a polar orbit, providing concentrated exploration of possible locations for water ice in the far north and south.

LRO's polar orbit provides a concentrated exploration of possible locations for water ice at the poles. The areas shown here in gold trace the path of LRO's orbit along the surface of the Moon — its ground track — after seven days. The Moon slowly rotates beneath LRO as it encircles the Moon once about every two hours, allowing LRO to scan the entire surface of the Moon every two weeks. LRO's ground tracks overlap densely at the poles (as indicated by the brighter gold shading), giving it especially good coverage of these areas. Image courtesy of NASA/Goddard Space Flight Center Scientific Visualization Studio. Some elevation data provided by JAXA/SELENE.

LRO is helping scientists and engineers understand the slope, roughness, and lighting of the terrain and identify potential landing hazards — and potential exploration sites rich in resources. Its cameras, a laser altimeter, and radar provide imagery and topographic maps.

The cameras (Lunar Reconnaissance Orbiter Camera or LROC) are taking high-resolution pictures of the Moon that will produce far more detailed maps of the Moon than are currently available. A laser (Lunar Orbiter Laser Altimeter or LOLA) probes the surface and creates a high-resolution topographical map of the Moon. Maps made from previous missions allow us to identify objects that are about 165 feet (about 50 meters) across for most of the Moon (the resolution is better in a limited number of places). With LOLA and LROC, we will finally have information that allows us to map the surface to within 1.5 feet (half a meter)! As LRO travels over the Moon's polar regions, its advanced radar (Miniature Radio Frequency or Mini-RF) is mapping the topography and roughness and searching for clues of water ice. The resulting strips of data are combined as a mosaic to depict the features of the poles.

LRO's advanced radar instrument (Mini-RF) gathers data in strips as the craft orbits the Moon's polar regions. The data is compiled as a mosaic to create a topographic map. Image courtesy of NASA.

The search for water and other resources is a main objective of the LRO mission. Previous missions to the Moon suggested that water ice may be present in the permanently shadowed regions of the poles. LRO is "sniffing" out a possible indicator of the presence of water — hydrogen — in the top 6 feet or so (2 meters) of the Moon's surface with its neutron detector (Lunar Exploration Neutron Detector or LEND). This helps scientists locate the position and the amount of frozen water on the Moon's surface.

LRO is also measuring the daytime and nighttime temperatures and identifying shadowed areas to help scientists find frozen water on the Moon's surface and near-surface with an instrument called the Diviner Lunar Radiometer Experiment (or Diviner for short).

LRO is wearing its own special version of night-vision goggles (Lyman Alpha Mapping Projector or LAMP) to measure ultraviolet light from star-shine that is reflected off the lunar surface. This tiny amount of reflected light helps scientists peer into permanently shadowed regions. Since ice reflects ultraviolet light a bit differently from rock, LAMP is also helping to identify frozen water.

This Lunar Prospector map of the Moon's south pole shows in blue where water or some other hydrogen-rich compound might be located. Image courtesy of NASA.

The LROC cameras are hunting for a source of oxygen as they photograph the Moon's topography and map the locations of certain minerals like ilmenite, which can be heated to release oxygen.

The LRO instruments are helping us characterize the temperatures on the lunar surface and how the temperatures change from day to night (Diviner). A spectrometer (Cosmic Ray Telescope for the Effects of Radiation or CRaTER) will determine the amount and types of radiation that the Moon receives. A plastic analog of human tissue will help scientists determine what types of shielding would protect astronauts in near-Earth environments.

While LRO peers down at the Moon with its variety of instruments, a separate NASA mission has hunted for water in a much more dramatic fashion — an impact! The Lunar CRater Observation and Sensing Satellite (LCROSS) launched on the same rocket as LRO. On October 9, 2009, the upper stage of the rocket impacted Cabeus crater, which is located at the Moon's south pole. The resulting impact sent up a plume of material that LCROSS spacecraft measured with its own suite of instruments. Four minutes after the Centaur impact, LCROSS impacted the surface, sending up another plume of material. Both plumes were observed by LRO and by Earth-based telescopes. The crater left by the LCROSS impacts were about a third of a football field across and less than 10 feet (about 3 meters) deep. A 22-pound (10-kilogram) meteorite would deliver about same energy as the LCROSS impact, and several of these natural impactors probably strike the Moon every few months.

The Moon is a New World to Discover

The Moon is covered with circular patches. Some of these are huge, covering more area than the state of Texas. Some are miniscule, smaller than the tip of a pin. All are caused by the innumerable meteoroids and comets bashing into the surface of the Moon over its 4.5-billion-year lifetime. The large ones you can see from your backyard were created when large meteoroids — asteroids — impacted the Moon. Smaller ones were made by smaller meteoroids. Impactors come in all sizes, and they create circular depressions — craters — of all sizes. These impacts pulverized rocks on the lunar surface, reducing them to a dusty, rock material called regolith that covers the Moon's surface — in some cases deeper than 50 feet (15 meters).

Image courtesy of NASA

The Moon has no atmosphere, so there is no wind and the sky is dark — like the Earth's sky on a clear night. There are extreme temperatures: an average of 225°F (107°C) during the day and –243°F (–153°C) at night. These extreme temperatures prevent liquid water from flowing on the surface: It would either vaporize into space or freeze. Any existent water is frozen in the areas that are permanently shadowed; these are the only areas not exposed to the Sun's heat during part of the lunar day.

Space is filled with radiation and charged particles, which are primarily from our Sun. These are deadly to humans unless they are protected from it. Earth's atmosphere and magnetic field offers us a safe-haven. The Moon, on the other hand, has no protective atmosphere and virtually no magnetic field, and so the radiation and charged-particle levels are very high.

Explorers of the lunar surface would move with the distinctive, leaping

'Moon walk. "Because it is less dense and smaller than Earth, the Moon has less gravity. The surface gravity is one-sixth Earth's gravity, so the simple push with the legs that is required to take a step on Earth propels the astronaut several feet high.

Astronauts living on the Moon would experience daylight for almost two Earth weeks and then darkness for the same time. The Moon orbits Earth once every 27 days — and turns on its axis once every 27 days. This means that the lunar "day" is equal to a lunar "year." It also means that the nearside faces Earth constantly. Since our Moon is tilted on its axis only a tiny amount, there essentially are no seasons.

We Have Only Begun to Understand the Moon

Based on earlier lunar missions, including the valuable visits by the Apollo astronauts, we have an understanding of the structure of the Moon's interior, types of rocks found on the lunar surface, the events that have shaped the Moon, and the conditions that exist at the surface. So why are we returning? The Apollo missions visited only six sites; imagine describing the whole Earth if you had only visited six places for a few days at each stop . . . you would be missing a lot of information! Only about 30% of the lunar surface was imaged in high resolution over the course of the entire Apollo program. Russia sent three robotic missions that returned samples, so we know about the materials at nine sites. Still, that's a whole lot of the Moon that is unexplored!

Orbiters have helped to add more detail to the picture. The Lunar Prospector and Clementine missions provided scientists with detailed information about the surface features and composition of much of the Moon's surface. The instruments on those missions were the very best, and they returned some exciting new data — particularly evidence for ice at shadowed regions at the poles. Now our instruments have gotten even better! The cameras and detectors onboard the LRO use new and refined technologies that provide much more detailed information than what was collected by earlier missions. LRO is one of several missions that are or were recently building upon our knowledge. India's Chandrayaan-1 (which included a NASA instrument), Japan's Kaguya, and China's Chang'e-1 all recently studied the Moon. (LRO itself has contributors from all over the country and from Russia.)

Future human colonies can mine the Moon for resources, such as oxygen, water, fuel, and building materials — but they will need to know where these resources are in more detail than we understand now. Based on earlier missions, we know that the rocks and soil contain aluminum, iron, silica, titanium, and other elements that can be used in buildings and solar panels. The loose lunar regolith can be used to make "lunar bricks" for building structures. The cameras (LROC) and neutron detector (LEND) are helping us map the presence of different elements and characterize the regolith.

Location of iron-rich rocks on the Moon (based on information from the Clementine mission instruments). Areas with increased iron tend to be in the lowlands — the basalt-filled impact basins. Image courtesy of the Clementine Science Group at the Lunar and Planetary Institute.

Location of titanium-rich rocks on the Moon (based on information from the Clementine mission instruments). Areas with increased titanium tend to be in the lowlands — the basalt-filled impact basins. Image courtesy of the Clementine Science Group at the Lunar and Planetary Institute.

Comets May Have Delivered Water to the Moon Over the Millennia

Scientists have evidence from previous missions that water ice may exist on the Moon's surface in some of the permanently shadowed regions; we need to confirm its presence. Water is a critical resource for sustained human exploration. If water ice exists it can be used for water and can be broken into its parts — oxygen and hydrogen for air and fuel. LRO is mapping the cold shadowed regions (with the LROC cameras; radometer, Diviner; and altimeter, LOLA) and identifying the materials on the Moon's surface (with the ultraviolet spectrometer, LAMP, and neutron detector, LEND) to locate and map water ice on the Moon. LCROSS excavated material in a deep crater at the lunar south pole. Such craters, permanently shadowed from the Sun's energy, may contain water ice, delivered by comets. In impacting the frigid depths of a crater and analyzing the plume that is thrown up, LCROSS has contributed to the search for water ice.

Comets made out of water ice and other materials have hit the Moon throughout its history. If the comet has struck in an area that does not receive much sunlight, like the south polar region of the Moon, that ice may still be there. Earlier missions to the Moon — Clementine and Lunar Prospector — provided evidence for the presence of water ice. The Lunar Prospector spacecraft detected large amounts of hydrogen in the polar regions, which scientists interpret to be coming from water ice. According to these data, frozen soil and ice at the poles may contain as much as 1–10 billion tons of water locked into deeply shaded craters. That is an amount equal to what is consumed by U.S. cities in 10 days. It would be enough to supply the population of a lunar base for a long time. In addition to sustaining life in a colony, water can be used for rocket fuel and for air by breaking it into its separate chemicals of hydrogen and oxygen.

Clementine image of the Moon's south pole showing where scientists believe water is present. Image courtesy of the Lunar and Planetary Institute; base map from the Clementine Project, USGS image processing.

The Moon holds the key to many scientific discoveries. LRO will allow us to learn much more about Earth's nearest neighbor. The Moon has preserved the geologic record of the early solar system and may give us clues about our origins. Its airless environment provides clear viewing for studying the universe.

Future Lunar Explorers Face Exciting Challenges

If humans are to live on the Moon, even for brief periods, they will need a wide range of support systems. They'll need a place to work, rest, and live that protects them from the cold and dangerous radiation of the space environment. They will need power, light, air, food, water, and heat. They'll need robust transportation and equipment able to operate in low temperatures and the hostile environment of space. They will need to be able to communicate with Earth, other colonies, and shuttles.

They will also need to deal with health issues. Reduced gravity is a challenge to people living on the Moon with one-sixth Earth's gravity. Under reduced gravity conditions, there is less "load" on bones and muscles, so living organisms lose bone mass, muscle tissue, and fluids. Even the heart — a muscle — loses mass because it does not have to work as hard. Humans on the Moon must exercise to maintain their bone and tissue mass so that they can return to Earth's gravity and function well. More research is needed to understand the effects of reduced gravity on the human body — and how to counter these effects.

Any habitat would have to provide shelter from the extreme temperatures and from incoming radiation. Moon bases may include subsurface buildings to increase protection from radiation and micrometeorites.

There probably would be three basic types of modules: habitation, laboratory, and support modules. The habitat would have sleeping quarters, a kitchen (or galley), and bathroom facilities. Windows would have to be small and made of multiple thick glass sheets to block cosmic radiation. Laboratory modules would be used for conducting experiments. A colony would also need several types of support modules and facilities, including a greenhouse to grow food; a power plant — either solar or nuclear; a place to store construction equipment and do maintenance; a central control, life support, and communications center; resource utilization facilities for processing mined materials; and a landing/launch pad. Accidents or fires could occur or meteorites might strike the base. If an accident occurs in a large structure, it might be necessary to abandon the entire building. However, in a module system, a damaged module could simply be isolated from the rest by closing the hatches shared with other modules, similar to the plan currently onboard the International Space Station.

The colonists will need some type of evacuation strategy, such as emergency escape transportation in the event of a severe accident.

The colony team would initially include scientists and engineers. These individuals would probably have many other capabilities, such as medical training and construction training. As the colony grew, other personnel would to be added. They would conduct research and experiments in the laboratories, work on colony construction, maintain the base, and mine resources. Medical specialists, cooks, safety specialists, administrative staff, and cleaning crews would be needed to support the efforts. These crews would be replaced on a regular basis in the same way as teams who work at Antarctic bases on Earth.

LRO and LCROSS Are Helping Us Determine Where to Explore in the Future

The Lunar Reconnaissance Orbiter and Lunar CRater Observation and Sensing Satellite missions will help us identify the most promising locations for mining for water and for minerals and will provide valuable, detailed data about the lunar environment. The areas of potential occupation need to be easily reached (the terrain needs to be somewhat smooth). The temperatures need to be in a range that can be controlled by our technology so that humans or robotic missions can operate. If humans are involved, radiation will have to be blocked by shielding either through a natural setting (for example, under thick lunar regolith or in lava tubes beneath the surface) or through buildings and spacesuits. The LRO will help us identify locations that are a balance between meeting these needs, accessing resources, and undertaking science and engineering experiments.